Decline of bumble bees in northeastern North America, with special focus on Bombus terricola

Concerns about the rapid and severe declines of many bumble bee (Bombus spp.) species in Europe, and more recently North America, have spurred research into the extent and possible causes for these losses. Drawing conclusions has been difficult due to a lack of long-term data, especially for specific regions that may have different factors at play than the global trend. In this study, 150 years of Bombus records in the state of New Hampshire from the University of New Hampshire Insect Collection were examined. This allowed for changes in abundance and distribution to be tracked over time, with focus on species designated of greatest conservation need by NH Fish & Game Department. Floral records also provided insight into the diet breadth of these species, which may affect their vulnerability. Evidence of drastic decline was found in Bombus affinis, Bombus fervidus, and Bombus terricola, as well as significant decline in Bombus vagans with data suggesting it has been ecologically replaced by Bombus impatiens over time. We suggest Bombus vagans receive future conservation consideration. Our analyses found a severe constriction of the geographic range of Bombus terricola to high elevation regions in the latter half of the 20th century, and its role as pollinator of several alpine plants necessitates immediate conservation action.